iPad Pro A9X chip breakdown shows 12 GPU cores and no L3 cache

posted by Michael H. / Nov 30, 2015, 2:29 PM

Apple is notoriously cagey when it comes to giving complete spec breakdowns of its devices, which leaves a lot of info to be supplied by teardowns, benchmarks, or partner slips after the fact. A manufacturer slip is how we first learned that the iPad Pro featured 4GB of RAM, and now a teardown is how we're getting a more complete breakdown of the A9X chip Apple has in the iPad Pro.

Chipworks and AnandTech worked hard over the Thanksgiving break to get images of the A9X chip and sort out what is there and what isn't. The breakdown confirms that TSMC made the SoC using a 16nm FinFET process, and the full chip is roughly 147mm2 in die size, which makes it slightly larger than the A6X and A8X, but smaller than the A5X.

A large amount of that space is dedicated to fitting in 12 GPU cores as part of Imagination's PowerVR 12 cluster Series7 design, which doesn't even exist on Imagination's roadmap. The A9 chip used Imagination's 6-core PVR GT7600, but the A9X is in a strange grey area between the 8 core GT7800 and 16 core GT7900, so it doesn't get a fancy name. But, when you combine those 12 GPU cores with the 128-bit memory bus, the A9X is capable of pushing memory bandwidth of 51.2GB/sec, which is pretty impressive.

The A9X SoC also doesn't have an L3 cache, which is somewhat surprising. AnandTech posits that the omission of the L3 cache was acceptable because of the size of the memory bandwidth on the chip, or it may be that Apple simply didn't need the power-saving afforded by the L3 cache. The answer is likely a bit of both, but we'll never get confirmation from Apple, so it'll have to remain an educated guess.

posted on Nov 30, 2015, 3:08 PM 0

posted on Nov 30, 2015, 3:19 PM 0

Posts: 62; Member since: May 17, 2013

just because Apple did it doesn't mean we have to hate on them. This chip is far more capable than anything on the market. It surpasses the Intel core i5 bridge graphics by miles. Yet it is in a thin package that doesn't heat, require something to cool it, or drain battery. All YouTubers agreed that this iPad passes the 10 hours video play back easily. So imo this chip is the most impressive chip on the market right now. Unfortunately the iPad pro doesn't have anything currently to take advantage of this chip

posted on Nov 30, 2015, 3:34 PM 8

Posts: 5029; Member since: Mar 30, 2015

In fact with no L3 cash multitasking will get a major hit if one of the app running use a lots of bandwith.
Its will slow down and lag like a bitch.
This is a way to make the chip irrelevent in 1 to 2 years.
Sure its has some nice spec and memory bandwith but no L3 really?
This is like having a 1000 hp engine running on 15 inch narrow tire.

Posts: 2137; Member since: Oct 18, 2011

posted on Nov 30, 2015, 4:25 PM 5

Posts: 368; Member since: Jun 13, 2012

Uh no the A9x is massive compared to Core M intel which is only 89mm and does more work than the A9X and consumes less power under load. Give Intel that much real estate and their graphics would blow past the A9X.

posted on Nov 30, 2015, 11:34 PM 1

Posts: 3960; Member since: Oct 21, 2014

All that power yet it still trails behind an Intel Core i3 Haswell in terms of on-screen graphics...
bit.ly/1O3fb5D
Not to talk of i5...battery efficiency, I think Intel is slowly figuring that out without compromising on the x86 architecture:
https://www.youtube.com/watch?v=OVHNmv_-7bQ

This copy is for your personal, non-commercial use only. You can order presentation-ready copies for distribution to your colleagues, clients or customers at https://www.parsintl.com/phonearena or use the Reprints & Permissions tool that appears at the bottom of each web page. Visit https://www.parsintl.com/ for samples and additional information.